1. Field of the Invention
The present invention relates generally to acoustic wave generators and, more particularly, to a high-frequency acoustic wave generator using a pulsed thermal radiation beam that is configured such that when a pulse beam formed by a light interrupter is directly radiated onto a porous material having a woven net or steel scrubber shape, thin wires of the porous material repeatedly rapidly thermally-expand and contract, whereby air in the space between the wires is momentarily heated and cooled, and the expansion and contraction of air is directly transmitted to an air column formed just adjacent to the porous material. By virtue of the above structure, the efficiency of the generator according to the present invention is markedly improved compared to the conventional technique, and the productivity is also greatly enhanced.
The present invention is configured to generate high-frequency (ultrasonic) waves from obtained acoustic waves and provide the acoustic waves to a variety of industrial fields including fields pertaining to sterilization, washing, etc.
2. Description of the Related Art
Generally, solar energy is used for air-conditioning or heating of buildings, lighting devices or power generation.
With regard to this, over the past half century studies on solar energy have been continuously conducted and many related techniques have already been commercialized. At present, various forms of solar energy conversion systems for improvement in efficiency are under study.
Meanwhile, the conversion of solar energy into acoustic energy, along with a solar tracking system, is opening a new chapter in technology using high-density solar energy. Most of this technology is focused on the development of thermoacoustic refrigerators.
Conventional thermoacoustic wave generators using solar light are configured such that a porous stack (solid block) is disposed in a transparent tube closed on one end thereof and thermoacoustic waves are generated by heating a portion thereof adjacent to the closed end of the transparent tube.
However, in conventional thermoacoustic wave generators, to generate high-frequency thermoacoustic waves, the size of the transparent tube must be reduced inversely proportional to the frequency of thermoacoustic waves, and a high thermal gradient between both ends of the porous stack must be maintained. Therefore, in practice it is very difficult to embody such conventional thermoacoustic wave generators. Referring to the result of research so far, it has been reported that the University of Utah, USA succeeded in producing a maximum acoustic wave of 3 kHz via this conventional technique.
In other words, it is no exaggeration to say that it is almost impossible to produce thermoacoustic waves in an ultrasonic wave range of 18 kHz or more using the above conventional technique.
Furthermore, research on generating thermoacoustic waves has focused on generating compression waves via a process of heating a very small micro-sized structure by momentarily applying Joule's heat resulting from electric energy to the structure and then cooling the structure. This process is repeated so that air surrounding the structure is expanded and cooled.
In an effort to overcome the problems of the conventional techniques pertaining to thermoacoustic wave generators, the applicant of the present invention proposed a thin metal plate membrane structure in Korean Patent Registration No. 10-1207380.
However, the technique of No. 10-1207380 is problematic in that the efficiency in producing high frequency is comparatively low because some solar light transmitted through a hole is lost in the air before it reaches the membrane structure. In addition, the size of a light interrupter must be greatly increased depending on the size of the thin metal plate. Therefore, it is substantially difficult to commercialize the technique.